1. Field of the Invention
The present invention relates to a column antenna apparatus and a method for manufacturing the same, and particularly relates to a metal layer with at least two spiral structures that is formed on of a hollow column body.
2. Description of the Related Art
Due to the development of the communication technology, a lot of electronic products that adopt the wireless communication technology are developed, such as cell phones, wireless Internet devices and personal digital assistant (PDA) etc. The requirements for the wireless communication devices come from the consumers has become higher and higher, such as the effect, the appearance, and dimension. For cell phones, the receiving frequency has developed from single, two to three, four frequencies. The consumers also requests the cell phones has the characteristics, including fresh appearance, small dimension, light weight, and easy carry. Moreover, the receiving-signal effect of the wireless communication devices is an important index for evaluating the wireless communication devices and the antenna apparatus is a key factor to determine the receiving-signal effect of the wireless communication devices. Therefore, it is an important factor to develop an antenna apparatus that has an excellent receiving-signal effect and meets with the requirement of fresh appearance and small dimension.
Referring to FIGS. 1 and 2, firstly a spiral coil 10 is formed (as shown in the FIG. 2). Then, a fastening layer 12 is formed by a projecting method with a plastic material. Therefore, the spiral coil 10 is fastened to a screw base 14. Finally, a plastic layer 16 is wrapped to provide the functions, including protection and good appearance.
However, the spiral coil 10 has the deformation problem during the shipment. The deformation of the spiral coil will affect the receiving frequency and the quality of the antenna. Furthermore, in the projecting process, the spiral coil 10 also is deformed due to the force come from the plastic material. The receiving frequency and the quality of the antenna may be changed due to the deformation of the spiral coil. Therefore, the quality of the antenna cannot be controlled well during the manufacturing process. Moreover, due to the structure of the antenna, the dimension of the antenna cannot be further shrunk.
Moreover, the known antenna structure has some defects such as its bandwidth of low frequency is narrow.